elsmandino
Posts: 35
Joined: Mon Dec 17, 2012 8:38 pm

Use a Pi to wake a server for TVHeadend scheduled recordings

Mon May 22, 2017 9:28 am

I am currently running TVHeadend on Openmediavault on my home server.

I wanted to save some power by having the server resume to sleep mode when not being used, but then wake up automatically for scheduled recordings.

Unfortunately, this is proving more difficult than I had hoped.

Is there any way I could use a Raspberry Pi to help, with this?

I was hoping that I could some how copy the timer schedule to the Pi, which could then wake up the Server, as necessary, via WOL.

Is this even possible?

ghans
Posts: 7882
Joined: Mon Dec 12, 2011 8:30 pm
Location: Germany

Re: Use a Pi to wake a server for TVHeadend scheduled record

Mon May 22, 2017 10:40 am

You can use the cron scheduler and the wakeonlan program for this.

cron is preinstalled (it is essential for many Distros , including Raspbian) , wakeonlan is just an apt-get away.

I doubt you will save much electricity though. A Pi can take up to 3W.


ghans
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elsmandino
Posts: 35
Joined: Mon Dec 17, 2012 8:38 pm

Re: Use a Pi to wake a server for TVHeadend scheduled record

Mon May 22, 2017 11:54 am

So you reckon it is possible to somehow pass the schedule list from TVHeadend to the cron list on the Pi and then have the Pi use this to wake the server (if it is not already awake) for recordings?

Powerwise, it should save me quite lot.

At the moment, my x86 server sits in an idle state (using about 32w) for about 50% of the time.

With a Pi being on 24/7 for 3w, this would mean that I would be able to drop the server to sleep mode (which is 2w) for 50% of the year.

ghans
Posts: 7882
Joined: Mon Dec 12, 2011 8:30 pm
Location: Germany

Re: Use a Pi to wake a server for TVHeadend scheduled record

Mon May 22, 2017 3:06 pm

You obviously need a tool which translates your existing schedule to "cron" format. What is it ? Perhaps someone already has done it ..

ghans
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elParaguayo
Posts: 1943
Joined: Wed May 16, 2012 12:46 pm
Location: London, UK

Re: Use a Pi to wake a server for TVHeadend scheduled record

Thu May 25, 2017 2:51 pm

I don't know much about openmediavault but, a while ago, I was running MythTV on an old desktop. I wrote a script that would set a BIOS wake time and then suspend the machine. The alarm was set for 5 mins before recording was due to start.

It worked beautifully but you'd need a motherboard that supports this feature (and, as I understand it, most post year 2000 motherboards do). If that works then you'd do away with the need for the raspberry pi here.
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